The solar charger is a stackable shield to Arduino compatible platforms, enabling adaptive battery power and acts as an energy harvester for in-field charging. You may use various batteries with voltages between 3.0V and 4.2V to shift up to 5V output, or connect a Li-ion battery and solar panel to form an autonomous sensor unit. The maximum current provided by the board is up to 600mA. An usb connector is also useful to charge the battery.